Production of esters of omega-hydroxyalkanesulfonic acids with alkenoic acids

ABSTRACT

Production of omega -hydroxyalkanesulfonic/alkenoic acid esters by reaction of alkali metal or alkaline earth metal salts of alkenoic acids with sultones in the presence of alcohols at a temperature below 45* C. The products are starting materials for the production of fibers, detergents, wetting agents, dispersing agents, ion exchangers and plastics.

United States Patent Pohlemann et al.

PRODUCTION OF ESTERS OF OMEGA- HYDROXYALKANESULFONIC ACIDS WITH ALKENOICACIDS Inventors: Heinz Pohlemann, Limburgerhof; Rolf Wurmb, Heidelberg,both of Germany Badische Anilin- & Soda-Fabrik Aktiengesellschaft,Ludwigshafen/Rhine. Germany Filed: Nov. 25, 1969 Appl. No.: 879,936

Assignee:

Foreign Application Priority Data [56] References Cited UNITED STATESPATENTS 3,024,221 3/1962 Le Ferre et a1, ..2 60/486 X FOREIGN PATENTS ORAPPLICATIONS 1,042,719 9/1966 Great Britain ..260/486 PrimaryExaminerLorraine A. Weinberger Assistant ExaminerPaul J. KillosAttorney-Johnston, Root, O'Keeffe, Keil, Thompson and Shurtleff [57]ABSTRACT Production of w-hydroxyalkanesulfonic/alkenoic' acid esters byreaction of alkali metal or alkaline earth metal salts of alkenoic acidswith sultones in the presence of alcohols at a temperature below 45 C.The products are starting materials for the production of fibers,detergents, wetting agents, dispersing agents, ion exchangers andplastics.

8-Claims, No Drawings PRODUCTION OF ESTERS OF OMEGA-HYDROXYALKANESULFONIC ACIDS WITH ALKENOIC ACIDS The invention relates toa process for the production of whydroxyalkanesulfonic/alkenoic acidesters by reaction of alkali metal or alkaline earth metal salts ofalkenoic acids with sultones in the presence of alcohols at atemperature below 45 C.

The reaction between alkali metal or alkaline earth metal salts ofcarboxylic acids and sultones which results in esters ofhydroxyalkanesulfonic acids with opening of the sulfonic acid lactonering is already known. US. Pat. Specification No. 2,964,557 disclosesthe reaction of methacrylates with sultones, advantageously in thepresence of organic solvents, for example ethanol or benzene. The rangefrom 70 to 145 C is given as the temperature range for the reaction.German Pat. Specification No. 894,116 describes similar reactionscarried out in the presence of water without the addition of inertorganic solvents and gives temperatures of from 80 C to 100 C in theExamples. The process disclosed in Belgian Pat. No. 593,819 is carriedout at from 40 to 130 C in the presence of inert sulfoxides and sulfoneswhich dissolve the salts of the carboxylic ester sulfonic acids formed.In all the Examples of the said Belgian patent reaction temperatures ofat least 50 to 55 C are mentioned.

In all the said methods impure end products are obtained which can onlybe purified with difficulty and uneconomically and the yield of pure endproduct is unsatisfactory. When the end products are esters derived frompolymerizable organic acids, for example acrylic or methacrylic acid,the use of high temperatures over long periods results in undesirablepolymerizations and other secondary reactions in spite of the additionof stabilizers. The byproducts formed in turn (when the unsaturatedesters containing sulfonate groups are to be used for polymerizationpurposes) contaminate the end product to be prepared by polymerizationand thus impair its properties.

It is an object of the invention to provide a new process for theproduction of esters of w-hydroxyalkanesulfonic acids which is easier tocarry out and more economical and gives better yields and higher purity.

These and other objects of the invention are achieved andw-hydroxyalkanesulfonic/alkenoic acid esters are prepared moreadvantageously in the reaction of alkali metal or alkaline earth metalsalts of alkenoic acids with sultones in the presence of organicsolvents by carrying out the reaction in the presence of an alcohol at atemperature of less than 45 C.

When sodium methacrylate and 1,3-propanesultone are used, the reactionmay be represented by the following equatron:

As compared with prior art methods, the process according to thisinvention gives w-hydroxyalkanesulfonic/alkenoic acid esters in betteryields and higher purity in a simpler and more economical manner. Havingregard to the state of the art it is surprising that these resultsshould be achieved at low temperature and in the presence of alcoholswhich are reactive as compared with other organic solvents withoutappreciable formation of byproducts. Because of their purity, thepolymerizable esters prepared by the process according to this inventionfacilitate polymerization and make possible the production of purepolymers.

Alkali metal and alkaline earth metal salts, particularly lithium,sodium, potassium, calcium and magnesium salts of alkenoic acids,especially polymerizable a,fi-alkenoic acids, are used as startingmaterials. Preferred alkenoic acids are linear or branchedmonocarboxylic or dicarboxylic acids having three to six carbon atoms,for example acrylic acid, methacrylic acid, maleic acid, fumaric acid,crotonic acid, citraconic acid, mesaconic acid, angelic acid and tiglicacid. Instead of salts of alkenoic acids, substances which form the sameduring the reaction, for example the corresponding alkenoic acids andthe corresponding alkali metal or alkaline earth metal hydroxides oralcoholates, may be used. 1n an advantageous embodiment of the process,alcoholates areemployed so that alcohol formed during the reactionserves as solvent to be used according to the invention and lessalcohol, or none at all, needs to be added. Alkali metal alkanolates,for example lithium methylate, sodium methylate and potassium ethylateare particularly suitable as alcoholates. m-alkanesultones, preferablylinear sultones having three to six carbon atoms, may also be used asstarting materials. Examples of suitable sultones are1,3-propanesu1tone, 1,3-butanesultone, 1,4-butanesultone,1,3-pentanesultone, 1,4-pentanesultone, 1,4-hexanesultone and1,6-hexanesultone. The sultones are generally used in stoichiometricamounts with reference to the alkenoic acid salts, but they may be usedin excess, for example in an excess of up to twice.

The reaction is carried out in the presence of an alcohol, preferably analkanol having one to six carbon atoms. Examples of suitable alcoholsare: ethanol, n-butanol, isobutanol, tert-butanol, cyclohexanol,propanol and particularly methanol. The alcohols are used as a rule inan amount of 3 to 12 moles per mole of alkenoic acid salt. The reactionis carried out at a temperature of less than 45 C, preferably less than40 C, particularly at from 20 to 40 C, at atmospheric orsuperatmospheric pressure, continuously or batchwise.

For example the starting materials may be reacted with one another asfollows: a mixture of a salt of an alkenoic acid and an alcohol, or ofalkenoic acid, alkali metal alcoholate and, if desired, alcohol, isbrought to the reaction temperature. Depending on the solubility of thealkenoate, the mixture is then present as a solution or containsundissolved salt. The sultone is then added in the course of fifteen toforty-five minutes and the mixture is cooled to 5 to -30 C; the endproduct which has crystallized out is separated by filtration.

Compounds which can'be prepared by the process according to theinvention are valuable starting materials for the production of fibers,detergents, wetting agents, dispersing agents, ion exchangers andplastics. For example they may serve as comonomers for the production ofpolyacrylonitrile fibers which are to be dyed with basic dyes. Thepublications mentioned above are referred to for further uses.

The invention is illustrated by the following Examples. The parts setout in the following Examples are parts by weight.

EXAMPLE 1 345 parts of methacrylic acid is slowly added at a temperatureof 10 to 20 C to a solution of 216 parts of sodium methylate in 700parts of methanol, the salt of the carboxylic acid thus beingprecipitated. The mixture .is then heated to 40 C and at from 40 to 45 C488 parts of 1,3-propanesultone is added. The sodium methacrylate firstprecipitated passes into solution during the addition of the sultone.When the mixture is cooled to 5 C, sodium methacryloxypropanesulfonatecrystallizes out in great purity. 735 parts of this substance isobtained percent of the theory).

The end product has the following analytical data after having beendried: molecular weight: 210

Calculated: Found:

C 36.5% C 36.5% H 4.78% H 5.1% 034.8% 0 34.8% S 13.9% S 13.8% Na 10.0%Na 10.1%

In chromatography of the end product on a cellulose-coated glass sheetwith the developing solvent alcohol:water:concentrated ammonia 80: 16:4,the end product is shown to be homogeneous (Rf value 0.75).

EXAMPLE 2 114 parts of lithium methylate is added to 216 parts ofacrylic acid dissolved in 400 parts of methanol. The mixture is heatedto 40 C. 366 parts of 1,3-propanesultone is added in portions in thecourse of 30 minutes and the mixture is stirred for another two hours atthis temperature. 800 parts of acetone is then added and the whole iscooled to 20 C. The deposited crystalline solid is suction filtered anddried. 437 parts (73 percent of the theory) of the lithium salt of'yacryloxypropanesulfonic acid is obtained. The end product has thefollowing analytical values: molecular weight: 214:

Calculated: O 40.0% S 16.0% Li 3.5% Found: 39.8% l6.l% 3.5%

We claim:

2. A process as claimed in claim I wherein said reaction is carried outwith said alkenoic acid and the alkali metal or alkaline earth metalalcoholate of said alkanol such that at least part of the alkanolsolvent is formed during the reaction of said acid with said alcoholate.

3. A process as claimed in claim 1 wherein the alkali or alkaline earthmetal of said salt is selected from the group consisting of sodium,potassium. lithium, calcium and magnesium.

4. A process as claimed in claim 1 wherein alkenoic acid is selectedfrom the group consisting of acrylic acid and methacrylic acid.

5. A process as claimed in claim 1 carried out with the sultone in anexcess of up to twice with reference to the alkenoate.

6. A process as claimed in claim 1 carried out with an alcohol in anamount of three to 12 moles per mole of alkenoate.

7. A process as claimed in claim 1 carried out at a temperature lowerthan 40 C.

8. A process as claimed in claim 1 carried out at a temperature of from20 to 40 C.

2. A process as claimed in claim 1 wherein said reaction is carried outwith said alkenoic acid and the alkali metal or alkaline earth metalalcoholate of said alkanol such that at least part of the alkanolsolvent is formed during the reaction of said acid with said alcoholate.3. A process as claimed in claim 1 wherein the alkali or alkaline earthmetal of said salt is selected from the group consisting of sodium,potassium, lithium, calcium and magnesium.
 4. A process as claimed inclaim 1 wherein alkenoic acid is selected from the group consisting ofacrylic acid and methacrylic acid.
 5. A process as claimed in claim 1carried out with the sultone in an excess of up to twice with referenceto the alkenoate.
 6. A process as claimed in claim 1 carried out with analcohol in an amount of three to 12 moles per mole of alkenoate.
 7. Aprocess as claimed in claim 1 carried out at a temperature lower than40* C.
 8. A process as claimed in claim 1 carried out at a temperatureof from 20* to 40* C.